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Development of a Centrifugal Technique for the Microbial Bioburden Analysis of Freon (CFC-11)

Tuesday, 01 January 2013

Commercial applications include pharmaceutical development and quality assurance, and
chemical manufacturing.

NASA Procedural Requirement
8020.12C entitled “Planetary Protection
Provisions for Robotic Extraterrestrial
Missions” states that the source-specific
encapsulated microbial density for
encapsulated organisms (div(0)) in nonmetallic
materials ranges from 1-30
spores/cm3. The standard laboratory
procedure, NASA Standard Procedures
for the Microbial Examination of Space
Hardware, NHB 5340.1B, does not provide
any direction into the methodologies
to understand the bioburden within
such a fluid as CFC-11 (Freon). This general
specification value for the Freon
would be applicable to the Freon charged
within the Mars Science Laboratory’s
(MSL’s) Heat Rejection System. Due to
the large volume required to fill this system,
MSL could not afford to conservatively
allocate 55.8% of the total spore
budget of the entire laboratory system
(rover, descent stage, cruise stage, and
aeroshell) of 5.00 × 105 spores at launch.

A novel filtration approach was developed
to analyze the Freon employing a
50 kDa molecular weight cutoff (MCO)
filter, followed by 0.22-μm pore-size filter
to establish a calculated microbial
bioburden.

Filtration of microorganisms from liquid
matrices is a standard laboratory approach. Due to the volatility of Freon, a
standard vacuum filtration unit would
not suffice because of the lack of a cold
trap on the vacuum unit. A more economical
approach had to be devised. The
two-pronged concentration approach is
advantageous due to the fact that it initially
concentrates the Freon from liters
to milliliters where it can then be feasibility
filtered and microbes extracted from
the filter. This is a technology improvement
over prior art as it defines the specific
parameters to concentrate microbial
organisms from a low-boiling-point fluid
such as Freon.

This work relates to the current MSL
mission but also has implications for
future NASA missions that will utilize the
same or similar heat rejection fluids. If the
same lot of material is utilized on a future
mission, then the experimentally derived
value can be directly used based on this
study (MSL-heritage). If a new lot or similar
material composition is used in a
future mission, then this technology can
be employed or modified accordingly to
accommodate such a fluid. This technology
development will allow for a heritage-based
starting point for fluids on other
missions in which a calculated microbial
bioburden is necessary.

This work was done by James N.
Benardini, Robert C. Koukol, Gayane A.
Kazarians, and Fabian Morales of Caltech
for NASA’s Jet Propulsion Laboratory. NPO-48303

This Brief includes a Technical Support Package (TSP).

Development of a Centrifugal Technique for the Microbial Bioburden Analysis of Freon (CFC-11) (reference NPO-48303) is currently available for download from the TSP library.

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